首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2763篇
  免费   178篇
  国内免费   10篇
耳鼻咽喉   36篇
儿科学   74篇
妇产科学   40篇
基础医学   317篇
口腔科学   120篇
临床医学   284篇
内科学   496篇
皮肤病学   207篇
神经病学   189篇
特种医学   200篇
外国民族医学   1篇
外科学   294篇
综合类   74篇
一般理论   1篇
预防医学   245篇
眼科学   36篇
药学   154篇
中国医学   6篇
肿瘤学   177篇
  2019年   26篇
  2018年   35篇
  2017年   31篇
  2016年   30篇
  2015年   58篇
  2014年   47篇
  2013年   89篇
  2012年   94篇
  2011年   109篇
  2010年   61篇
  2009年   82篇
  2008年   79篇
  2007年   81篇
  2006年   82篇
  2005年   79篇
  2004年   80篇
  2003年   65篇
  2002年   56篇
  2001年   65篇
  2000年   69篇
  1999年   80篇
  1998年   73篇
  1997年   83篇
  1996年   68篇
  1995年   62篇
  1994年   58篇
  1993年   54篇
  1992年   61篇
  1991年   65篇
  1990年   76篇
  1989年   60篇
  1988年   53篇
  1987年   82篇
  1986年   70篇
  1985年   49篇
  1984年   40篇
  1983年   33篇
  1982年   28篇
  1980年   24篇
  1979年   25篇
  1978年   20篇
  1977年   19篇
  1976年   26篇
  1974年   23篇
  1973年   25篇
  1972年   19篇
  1971年   21篇
  1970年   21篇
  1913年   30篇
  1912年   25篇
排序方式: 共有2951条查询结果,搜索用时 15 毫秒
81.

Background

Malignant bone tumors should be treated within interdisciplinary treatment concepts. The prognosis of pathological fractures is on the whole relatively poor because the fracture is indicative of a large and highly aggressive tumor and the hematoma associated with the fracture could possibly result in spreading of the tumor into the surrounding soft tissues.

Objectives

This article summarizes the current interdisciplinary treatment concepts under special consideration of pathological fractures in primary bone tumors.

Methods

A selective literature search was carried out taking own experience into consideration.

Results

Due to the multimodal therapy approach for osteosarcoma and Ewing’s sarcoma, the 5-year survival rate could be increased to 60-70 %.

Conclusion

The therapeutic treatment should always be carried out within the framework of an interdisciplinary, oncological bone expert team, especially in cases of pathological fractures of malignant bone tumors.  相似文献   
82.

INTRODUCTION

The Triathlon® (Stryker, Kalamazoo, MI, US) total knee replacement was designed to improve patient function and survivorship. The aim of this study was to determine whether the Triathlon® prosthesis produces better patient reported outcomes than a previous design by the same manufacturer, the Kinemax Plus.

METHODS

The outcome of 233 knees of patients with a mean age of 68 years (range: 40–80 years) who received the Kinemax Plus prosthesis were compared with the outcomes of 220 knees of patients with a mean age of 70 years (range: 42–90 years) who received the Triathlon® prosthesis. Data were collected via postal questionnaire prior to surgery as well as at 8–12 weeks and at 1 year following surgery. Validated questionnaires were used including the WOMAC® (Western Ontario and McMaster Universities) pain and function scales, the Knee injury and Osteoarthritis Outcome Score quality of life scale and the self-administered patient satisfaction scale.

RESULTS

This study found that patients who had the Triathlon® prosthesis had significantly better pain relief (p<0.0001), function (p=0.028), knee related quality of life (p<0.0001) and satisfaction (p=0.0003) at three months after surgery than those who received the Kinemax Plus prosthesis. In addition, knee related quality of life (p=0.002) and satisfaction (p=0.021) were significantly higher at one year after surgery in Triathlon® patients.

CONCLUSIONS

The findings suggest that return to function and reduction in pain may occur more quickly in patients with a Triathlon® prosthesis than in those with the Kinemax Plus.  相似文献   
83.
84.
Deleterious mutations are of fundamental importance to all aspects of organismal biology. Evolutionary geneticists have expended tremendous effort to estimate the genome-wide rate of mutation and the effects of new mutations on fitness, but the degree to which genomic mutational properties vary within and between taxa is largely unknown, particularly in multicellular organisms. Beginning with two highly inbred strains from each of three species in the nematode family Rhabditidae (Caenorhabditis briggsae, Caenorhabditis elegans, and Oscheius myriophila), we allowed mutations to accumulate in the relative absence of natural selection for 200 generations. We document significant variation in the rate of decay of fitness because of new mutations between strains and between species. Estimates of the per-generation mutational decay of fitness were very consistent within strains between assays 100 generations apart. Rate of mutational decay in fitness was positively associated with genomic mutation rate and negatively associated with average mutational effect. These results provide unambiguous experimental evidence for substantial variation in genome-wide properties of mutation both within and between species and reinforce conclusions from previous experiments that the cumulative effects on fitness of new mutations can differ markedly among related taxa.  相似文献   
85.
RNase P, an enzyme with RNA and protein subunits, cleaves tRNA precursor molecules to form the 5' termini of mature tRNAs in both prokaryotes and eukaryotes. Rabbit antibodies made against the protein subunit, C5 protein, of Escherichia coli RNase P bound RNase P protein from E. coli and Bacillus subtilis in immunoblots and solid-phase immunoassays. These rabbit anti-C5 antibodies also bound a protein (Mr approximately 40,000) in preparations of RNase P from human (HeLa) cells and depleted the enzymatic activity from preparations of RNase P from both human and E. coli cells. Finally, rabbit anti-C5 antibodies immunoprecipitated from crude extracts of human cells a ribonucleoprotein complex containing H1 RNA, the putative RNA component of human RNase P. These results show that an antigenic determinant is shared by C5 protein from E. coli RNase P and a protein component of RNase P from human cells.  相似文献   
86.
Many studies of caloric restriction (CR) in rodents and lower animals indicate that this nutritional manipulation retards aging processes, as evidenced by increased longevity, reduced pathology, and maintenance of physiological function in a more youthful state. The anti-aging effects of CR are believed to relate, at least in part, to changes in energy metabolism. We are attempting to determine whether similar effects occur in response to CR in nonhuman primates. Core (rectal) body temperature decreased progressively with age from 2 to 30 years in rhesus monkeys fed ad lib (controls) and is reduced by approximately 0.5 degrees C in age-matched monkeys subjected to 6 years of a 30% reduction in caloric intake. A short-term (1 month) 30% restriction of 2.5-year-old monkeys lowered subcutaneous body temperature by 1.0 degrees C. Indirect calorimetry showed that 24-hr energy expenditure was reduced by approximately 24% during short-term CR. The temporal association between reduced body temperature and energy expenditure suggests that reductions in body temperature relate to the induction of an energy conservation mechanism during CR. These reductions in body temperature and energy expenditure are consistent with findings in rodent studies in which aging rate was retarded by CR, now strengthening the possibility that CR may exert beneficial effects in primates analogous to those observed in rodents.  相似文献   
87.
BackgroundThe clinical course of COVID-19 includes multiple disease phases. Data describing post-hospital discharge outcomes may provide insight into disease course. Studies describing post-hospitalization outcomes of adults following COVID-19 infection are limited to electronic medical record review, which may underestimate the incidence of outcomes.ObjectiveTo determine 30-day post-hospitalization outcomes following COVID-19 infection.DesignRetrospective cohort studySettingQuaternary referral hospital and community hospital in New York City.ParticipantsCOVID-19 infected patients discharged alive from the emergency department (ED) or hospital between March 3 and May 15, 2020.MeasurementOutcomes included return to an ED, re-hospitalization, and mortality within 30 days of hospital discharge.ResultsThirty-day follow-up data were successfully collected on 94.6% of eligible patients. Among 1344 patients, 16.5% returned to an ED, 9.8% were re-hospitalized, and 2.4% died. Among patients who returned to the ED, 50.0% (108/216) went to a different hospital from the hospital of the index presentation, and 61.1% (132/216) of those who returned were re-hospitalized. In Cox models adjusted for variables selected using the lasso method, age (HR 1.01 per year [95% CI 1.00–1.02]), diabetes (1.54 [1.06–2.23]), and the need for inpatient dialysis (3.78 [2.23–6.43]) during the index presentation were independently associated with a higher re-hospitalization rate. Older age (HR 1.08 [1.05–1.11]) and Asian race (2.89 [1.27–6.61]) were significantly associated with mortality.ConclusionsAmong patients discharged alive following their index presentation for COVID-19, risk for returning to a hospital within 30 days of discharge was substantial. These patients merit close post-discharge follow-up to optimize outcomes.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11606-021-06924-0.KEY WORDS: COVID-19, mortality, re-admission, discharge  相似文献   
88.
Objectives

This multicenter prospective clinical trial investigated immediately provisionalized, anodized, conical connection, tapered implants with platform shifting in maxillary anterior and premolar sites.

Materials and methods

Patients requiring single-tooth implant-supported restorations in maxillary anterior and premolar sites were enrolled. Implants were immediately provisionalized and evaluated at insertion, 6 months, and annually thereafter. Outcome measures were marginal bone level change (ΔMBL), cumulative survival rate (CSR), and success rate, soft-tissue parameters, and oral health impact profile (OHIP). ΔMBL and Pink Esthetic Score were analyzed using Wilcoxon signed-rank tests. CSR was calculated using life table analysis. Other soft-tissue parameters were analyzed using sign tests.

Results

Of 94 enrolled patients (99 implants), 84 (88 implants) attended the 3-year follow-up. After an initial bone loss between implant insertion and 6 months (− 0.92 ± 1.23 mm), bone levels stabilized from 6 months to 3 years (0.13 ± 0.94 mm) with no significant change. The 3-year CSR was 98.9%, and the cumulative success rate was 96.9%. Papilla index scores of 2 or 3 were observed at 88.6% of sites at the 3-year visit compared with 32.8% at implant insertion. Improvements were observed for all other outcomes, including bleeding on probing, esthetics, plaque, and OHIP.

Conclusions

This restorative protocol was associated with high primary stability, patient satisfaction, stable bone levels, and an overall improvement of the soft tissue outcomes over a 3-year period.

Clinical relevance

The presented treatment is a viable option for single-tooth restorations of maxillary anterior teeth and premolars with successful short- to mid-long-term clinical outcomes.

  相似文献   
89.
Histories of childhood trauma have been reported previously in bulimic subjects but no study to date has assessed how these experiences may affect response to fluoxetine. Thirty outpatient subjects in a placebo-controlled trial of 60 mg of fluoxetine for the treatment of bulimia nervosa completed the Dissociative Experiences Scale and a self-report instrument assessing trauma. Response to treatment was measured with the Hamilton Depression Scale-17 (HAMD-17), the CGI, the PGI, and the change in number of binges per day. Subjects taking fluoxetine with histories of physical abuse showed a significantly greater drop in HAMD-17 scores than those without such histories. No relationship between a reported history of abuse and the response of binging to fluoxetine was found. A history of abuse does not appear to predict the response of hinging to fluoxetine but may predict a greater response of nonspecific symptoms like depression. © 1994 by John Wiley & Sons, Inc.  相似文献   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号